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. 2022 Jul 12;10(4):e01157-22. doi: 10.1128/spectrum.01157-22

TABLE 5.

Sensitivities of SARS-CoV-2 antigen LFTs relative to NAAT for VOC detection according to the viral load, as assessed by the CT value in RT-PCR

Variant CT value Sensitivity (95% CI) (%) of test
AAZ AMP Novel Biospeedia R-Biopharm Siemens Abbott Biosynex
Alpha ≤20 100 (89.1–100) 96.9 (83.8–99.9) 100 (88.8–100) 96.8 (83.3–99.9) 100 (88.1–100) 100 (89.1–100) 100 (89.1–100) 100 (89.1–100)
21–25 87.5 (61.7–98.4) 93.8 (69.8–99.8) 86.7 (59.5–98.3) 93.3 (68.1–99.8) 73.3 (44.9–92.2) 87.5 (61.7–98.4) 60.0 (32.3–83.7) 87.5 (61.7–98.4)
26–30 50.0 (6.8–93.2) 75.0 (19.4–99.4) 25.0 (0.6–80.6) 50.0 (6.8–93.2) 50.0 (6.8–93.2) 50.0 (6.8–93.2) 0 (0–60.2) 25.0 (0.6–80.6)
>30 0 (0–84.2) 0 (0–84.2) 0 (0–84.2) 0 (0–84.2) 50.0 (1.3–98.7) 0 (0–84.2) 0 (0–84.2) 0 (0–84.2)
≤25 95.8 (85.7–99.5) 95.8 (85.7–99.5) 95.7 (85.2–99.5) 95.7 (85.2–99.5) 90.9 (78.3–97.5) 95.8 (85.7–99.5) 87.2 (74.3–95.2) 95.8 (85.7–99.5)
≤30 92.3 (81.5–97.9) 94.2 (84.1–98.8) 90.0 (78.2–96.7) 92.0 (80.8–97.8) 87.5 (74.8–95.3) 92.3 (81.5–97.9) 80.4 (66.9–90.2) 90.4 (79.0–96.8)
Any 88.9 (77.4–95.8) 90.7 (79.7–96.9) 86.5 (74.2–94.4) 88.5 (76.6–95.6) 86.0 (73.3–94.2) 88.9 (77.4–95.8) 77.4 (63.8–87.7) 87.0 (75.1–94.6)
 
Beta ≤ 20 100 (29.2–100) 100 (29.2–100) 100 (29.2–100) 100 (29.2–100) 100 (29.2–100) 100 (29.2–100) 66.7 (9.4–99.2) 100 (29.2–100)
21–25 100 (73.5–100) 100 (73.5–100) 100 (73.5–100) 100 (73.5–100) 100 (73.5–100) 100 (73.5–100) 91.7 (61.5–99.8) 100 (73.5–100)
26–30 66.7 (22.3–95.7) 83.3 (35.9–99.6) 66.7 (22.3–95.7) 83.3 (35.9–99.6) 66.7 (22.3–95.7) 66.7 (22.3–95.7) 66.7 (22.3–95.7) 50.0 (11.8–88.2)
>30
≤25 100 (78.2–100) 100 (78.2–100) 100 (78.2–100) 100 (78.2–100) 100 (78.2–100) 100 (78.2–100) 86.7 (59.5–98.3) 100 (78.2–100)
≤30 90.5 (69.6–98.8) 95.2 (76.2–99.9) 90.5 (69.6–98.8) 95.2 (76.2–99.9) 90.5 (69.6–98.8) 90.5 (69.6–98.8) 81.0 (58.1–94.6) 85.7 (63.7–97.0)
Any 88.9 (77.4–95.8) 90.7 (79.7–96.9) 86.5 (74.2–94.4) 88.5 (76.6–95.6) 86.0 (73.3–94.2) 88.9 (77.4–95.4) 77.4 (63.8–87.7) 87.0 (75.1–94.6)
Delta ≤20 97.1 (84.7–99.9) 100 (89.7–100) 100 (89.7–100) 100 (89.7–100) 94.1 (80.3–99.3) 100 (89.7–100) 94.1 (80.3–99.3) 97.1 (84.7–99.9)
21–25 84.6 (54.6–98.1) 100 (75.3–100) 92.3 (64.0–99.8) 100 (75.3–100) 61.5 (31.6–86.1) 84.6 (54.6–98.1) 69.2 (38.6–0.9) 92.3 (64.0–99.8)
26–30 0 (0–41) 42.9 (9.9–81.6) 14.3 (0.4–57.9) 14.3 (0.4–57.9) 28.6 (3.7–71.0) 14.3 (0.4–57.9) 0 (0–41.0) 0 (0–41.0)
>30
≤25 93.6 (82.5–98.7) 100 (92.5–100) 97.9 (88.7–99.9) 100 (92.5–100) 85.1 (71.7–93.8) 95.7 (85.5–99.5) 87.2 (74.3–95.2) 95.7 (85.5–99.5)
≤30 81.5 (68.6–90.7) 92.6 (82.1–97.9) 87.0 (75.1–94.6) 88.9 (77.4–95.8) 77.8 (64.4–88.0) 85.2 (72.9–93.4) 75.9 (62.4–86.5) 83.3 (70.7–92.1)
Any 88.9 (77.4–95.8) 90.7 (79.7–96.9) 86.5 (74.2–94.4) 88.5 (76.6–95.6) 86.0 (73.3–94.2) 88.9 (77.4–95.8) 77.4 (63.8–97.7) 87.0 (75.1–94.6)
Omicron (BA.1) ≤20 100 (71.5–100) 100 (71.5–100) 100 (71.5–100) 100 (71.5–100) 100 (71.5–100) 100 (71.5–100) 90.9 (58.7–99.8) 90.9 (58.7–99.8)
21–25 100 (76.8–100) 100 (76.8–100) 100 (76.8–100) 100 (76.8–100) 85.7 (57.2–98.2) 100 (76.8–100) 92.9 (66.1–99.8) 92.9 (66.1–99.8)
26–30 69.2 (38.6–90.9) 76.9 (46.2–95.0) 69.2 (38.6–90.9) 69.2 (38.6–90.9) 38.5 (13.9–68.4) 61.5 (31.6–86.1) 30.8 (9.1–61.4) 38.5 (13.9–68.4)
>30 8.3 (0.2–38.5) 8.3 (0.2–38.5) 8.3 (0.2–38.5) 8.3 (0.2–38.5) 8.3 (13.9–68.4) 8.3 (0.2–38.5) 8.3 (0.2–38.5) 8.3 (0.2–38.5)
≤25 100 (86.3–100) 100 (86.3–100) 100 (86.3–100) 100 (86.3–100) 92.0 (74.0–99.0) 100 (86.3–100) 92.0 (74.0–99.0) 92.0 (74.0–99.0)
≤30 89.5 (75.2–97.1) 92.1 (78.6–98.3) 89.5 (75.2–97.1) 89.5 (75.2–97.1) 73.7 (56.9–86.6) 86.8 (71.9–95.6) 71.1 (54.1–84.6) 73.7 (56.9–86.6)
Any 70.0 (55.4–82.1) 70.0 (55.4–82.1) 70.0 (55.4–82.1) 70.0 (55.4–82.1) 58.0 (43.2–71.8) 68.0 (53.3–80.5) 56 (41.3–70.0) 58.0 (43.2–71.8)